Sweet Itch in Horses: Causes, Symptoms, and What Actually Helps in Summer

What is Sweet Itch in Horses?

Sweet itch is an allergic skin condition in horses caused by bites from small flying insects, most commonly Culicoides midges. It is also known as insect bite hypersensitivity or summer eczema.

For most horses, insect bites are simply irritating. But in horses with sweet itch, the immune system overreacts to proteins in the insect’s saliva. This triggers intense itching, inflammation and discomfort.

Once a horse has become sensitised, even a small number of bites can be enough to cause a flare-up. That is why some horses seem to go from comfortable to incredibly itchy very quickly as the weather warms up.

Sweet itch is one of the most common allergic skin diseases in horses, and World Horse Welfare notes that it affects around 5% of the UK horse population.

What Causes Sweet Itch in Horses?

Sweet itch is caused by an allergic reaction to insect bites, not by dirt, poor grooming or poor horse care.

The main trigger is usually biting midges, although other biting insects can also contribute. When these insects bite, they leave saliva in the skin. In horses with sweet itch, the body treats this saliva as a threat and produces an exaggerated allergic response.

This is why prevention is so important. Once the allergic reaction has started, the itching can become difficult to control. Horses may rub against fences, stable doors, trees or field shelters, which can then damage the skin further.

Sweet itch is usually worse during the warmer months because midges and other biting insects are more active. Hot, humid, still conditions can make things worse, especially around dawn and dusk when midge activity is often higher. The British Horse Society recommends sheltering affected horses from dusk until after dawn, especially during hot and humid weather.

Research from the University of Liverpool's equine dermatology studies explains why, once a horse is sensitised, even a few bites can trigger a full allergic response.

Why does sweet itch peak in spring and summer?

Sweet itch is one of the most common and frustrating summer skin problems in horses. It often appears suddenly as the weather warms and insects become more active, leaving owners unsure whether they are dealing with flies, mites, poor skin health, or something more serious.

For some horses, the first signs may be quite mild. You might notice them rubbing their tail more than usual, flicking their skin, or becoming restless in the field. But if the bites continue, the irritation can quickly build.

By summer, affected horses may be rubbing daily, losing hair or developing sore patches. This is why it is better to start prevention early, before the itching becomes severe.

If your horse gets sweet itch every year, waiting until they are already rubbing is usually too late. Fly protection should ideally begin before midge season is in full swing.

What Does Sweet Itch Look Like?

Sweet itch usually affects the areas where midges like to feed, or where the horse can easily rub once itchy.

Common signs include intense rubbing, especially around the mane and tail. You may notice broken hairs, bald patches, flaky skin or thickened areas where the skin has been irritated for a long time.

Some horses also become sore around the withers, belly, face, ears or chest. Others may stamp, twitch, roll more often, or seem generally unsettled when insects are active.

In more severe cases, the skin can become raw, weepy or infected. If this happens, your horse may need veterinary treatment rather than just fly control or soothing products.

Sweet itch can look similar to other skin issues, including lice, mites, ringworm, rain scald, allergic reactions, rug rubs or general fly irritation. If this is the first time your horse has shown symptoms, or the signs are severe, it is worth speaking to your vet before assuming it is sweet itch.

Common signs include:

• Intense itching and rubbing

• Hair loss along the mane, tail, belly and withers

• Thickened, scurfy or sore skin

• Broken hairs or raw patches caused by repeated rubbing

Can Horses Get Sweet Itch in the Winter?

Sweet itch is usually much better in winter because biting insects are less active.

However, that does not always mean the problem has fully gone away. Skin damage from summer rubbing can take time to heal, and some horses may still have thickened, sensitive or scurfy skin after the main midge season has passed.

Winter is also a good time to plan ahead. If your horse has had sweet itch before, you can use the quieter months to check rugs, review turnout plans and make sure you have fly protection ready before spring arrives.

Sweet itch is seasonal, but good management is year-round.

How to Treat Sweet Itch in Horses

There is no single permanent cure for sweet itch. The aim is to reduce insect bites, calm irritated skin and stop rubbing from causing further damage.

The most effective approach usually combines several things at once: fly prevention, physical barriers, stable and field management, and skin support.

1. Fly Prevention (Essential) - Start fly control before symptoms flare up

Reducing insect bites reduces allergic triggers. This usually involves:

• Daily use of horse fly repellent sprays

• Stable management during peak midge times, particularly dawn and dusk

• Environmental control where possible

You can browse our full range of Horse Fly Repellents here.

2. Use sweet itch rugs, fly masks and fly boots

Physical barriers can make a big difference for horses with sweet itch.

A standard fly rug may help with general fly irritation, but horses with sweet itch often need more coverage. Sweet itch rugs are designed to cover more of the body, including areas such as the neck, belly and tail base, where affected horses commonly rub.

Fly masks can help protect the face, eyes and ears, while fly boots may help horses that stamp, rub or react strongly around the legs.

However, rugs and masks are not perfect. They can slip, leave gaps, cause rubs or become too warm if not fitted and managed properly. They also need checking every day to make sure your horse is comfortable and that insects are not getting trapped underneath.

The British Horse Society advises using fly rugs and masks that cover as much of the horse as possible to reduce exposed skin. It also notes that zebra-print fly rugs may help reduce fly bites by confusing flies.

3. Manage turnout around midge activity

Where and when your horse is turned out can affect how much they are bitten.

Midges are often most active around dawn and dusk, particularly in warm, still and humid conditions. If your horse’s sweet itch is difficult to manage, it may help to stable them during peak midge times and turn them out when insect pressure is lower.

Field choice can also make a difference. Midges tend to prefer damp, sheltered areas, especially near standing water, hedges, woodland or boggy ground. If possible, choose breezier, more open turnout areas away from stagnant water.

Stable management can also help. Fine mesh over doors or windows, good ventilation and fans may reduce midge access, as midges are weak fliers. This will not remove the problem completely, but it can reduce the number of bites your horse receives.

4. Skin Support

Once your horse’s skin is itchy or damaged, it needs gentle support.

Soothing skin products may help calm irritation, soften dry patches and protect areas that have been rubbed. Products containing ingredients such as aloe vera may be useful for mild irritation, provided the skin is not badly broken and the product is suitable for horses.

However, topical products are not a replacement for bite prevention. If midges continue to bite, the allergic reaction will keep being triggered.

Avoid applying strong fly repellents, heavily fragranced products or harsh ingredients to raw, bleeding or infected skin unless the product specifically says it is suitable. Broken skin may sting, become more inflamed, or need veterinary treatment.

Products like aloe vera for horses skin, can help calm irritated skin and protect damaged areas while healing takes place.

5. Consistency Over Switching

Frequent changes between products often lead to poor results. Consistent use of an appropriate management routine is far more effective.

Practical Advice: What To Do & What to Avoid

What to Do

• Start fly control before signs appear in spring
• Apply fly repellent consistently, following manufacturer instructions
• Focus application on high‑risk areas such as the mane, tail head and belly
• Reapply after sweating or rainfall

What to Avoid

• Waiting until severe rubbing has started
• Applying strong repellents to already broken skin unless stated as suitable
• Assuming rugs or supplements alone will stop insects
• Using products more often than advised

Many horses improve significantly when fly protection starts early, but flare‑ups can return quickly if management becomes inconsistent during warm spells.

Frequently Asked Questions:

If your horse shows signs of sweet itch or has a history of summer itching, early and consistent fly control is the most important action you can take.

You can find some of our fly-repelling favourites from brands like SWITCH, NAF, and Audevard below.